The present invention relates to a new watermelon (Citrullus lanatus) cultivar designated watermelon line Ace Plus. All publications cited in this application are herein incorporated by reference.
There are numerous steps in the development of any novel, desirable plant germplasm. Plant breeding begins with the analysis and definition of problems and weaknesses of the current germplasm, the establishment of program goals, and the definition of specific breeding objectives. The next step is selection of germplasm that possess the traits to meet the program goals. The goal is to combine in a single variety or hybrid an improved combination of desirable traits from the parental germplasm. These important traits may include increased head size and weight, higher seed yield, improved color, resistance to diseases and insects, tolerance to drought and heat, and better agronomic quality.
Watermelon is a member of the Cucurbitaceae family and is a vine-like flowering plant thought to have originated in southern Africa. Watermelon is an annual plant with long, weak, trailing or climbing stems that is grown for its large edible fruit. The fruit has a thick rind and fleshy center that is red, orange, pink, yellow, green or white. The fruit is rich in vitamins A and C and can be eaten raw or cooked in various ways. There are over 1,200 varieties of watermelon worldwide, which range in weight from less than one to more than 90 kilograms.
Successful watermelon production depends on attention to various cultural practices. This involves soil management practices with special attention to proper fertilization, crop establishment with appropriate spacing, weed control, the introduction of bees for pollination, and suitable pollenizers for seedless watermelon, irrigation and pest management. Watermelon fruit size and shape; rind color; thickness and toughness; seed size, color and number; and flesh color, texture, soluble solids and freedom from fruit defects are all important characteristics to be considered in selection of watermelon varieties. In addition, seedless watermelons should be free of hard seeds and have undeveloped seeds that are small and innocuous.
Watermelon pollination is essential to the production of fruit. The flowers of watermelon plants are unisexual, with male and female flowers occurring on the same plant (monoecious). In order to set fruit, pollen from the male flower must be transferred to a female flower on that plant or another plant in the field. This pollen transfer is accomplished by several naturally occurring insects, but most effectively by the honeybee.
Seedless watermelon plants are triploid and are produced by crossing a tetraploid (2n=4x=44 chromosomes) inbred line as the female parent with a diploid (2n=2x=22) inbred line as the male parent of the hybrid; the resulting hybrid is a triploid (2n=3x=33). Triploid plants have three sets of chromosomes, and three sets cannot be divided evenly during meiosis. This results in nonfunctional female and male gametes although the flowers appear normal. Since the triploid hybrid is female sterile, the fruit induced by pollination tend to be seedless. As the pollen in triploid male flowers is not viable and female flowers in triploid plants require viable pollen to set fruit, it follows that there must be separate diploid (seeded) pollenizer plants available to provide pollen.
Triploid watermelon is mainly pollinated by bees and other insects that hop from flower to flower and distribute pollen from seeded pollenizer plants to triploid hybrid plants. Because watermelon flowers open only for a short time, it is essential that bees and pollens are present during pollination. It is also essential that the full-flowering period of the seedless plants (which takes about 3-4 weeks) should match with the full-flowering period of the pollenizer plants, in order to have plenty of pollen available during pollination. Lack of pollen during full flowering of seedless watermelon plants will have negative effect on the total yield and fruit quality. Therefore, early-maturing seedless watermelon hybrids should be combined with early and prolonged-flowering pollenizer plants to achieve high yield and quality watermelon production in commercial production fields.
Seeded watermelon plants take up space, nutrients and water in the field that farmers would rather devote to seedless plants. As a results, farmers have increasingly turned to varieties of seeded watermelons that produce pollen to fertilize the seedless plants, but that also grow very small, inedible fruit that does not need to be harvested and does not take up much space in the field. These varieties are called “pollenizers” because they are grown solely to provide pollen for the seedless watermelons.
Watermelon plants are susceptible to numerous diseases that attack the roots, foliage, and fruit. The most common diseases of watermelon are anthracnose, fusarium wilt, downy mildew, gummy stem blight, root-knot nematode and virus diseases. Disease control and production of resistant lines are thus essential for the production of high quality watermelons.
Therefore, developing improved inbred watermelon lines having early flowering, an increased number of flowers and an increased length of flowering period, producing an increased yield of marketable triploid fruit when used as a parent of a pollenizer, and having resistance to diseases, is highly desirable.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification.